1. Field of the Invention
The invention relates to a cylinder, in particular, a rotary printing-machine sheet-guiding cylinder, having an outer diameter which, because the cylinder has an elastically deformable, partly circular cylinder jacket, is variable by an adjusting device.
In the instant application, the cylinder jacket has been described as being "partly circular". This does not mean that only mathematically exact partially circular contours are provided, but rather, that contours which are formed approximately as a partial circle or, in other words, have certain out-of-round features are also included.
A cylinder of the type referred to in the introduction hereto is disclosed in German Patent 44 34 828. The cylinder known from this prior art reference has an elastically deformable cylinder jacket, which is supported by rollers 4 resting on inclined faces of a positioning disk 5 which is rotatable relative to an inner cylinder base body. If a rotation is effected, the radial spacing of the rollers from the cylinder base body is changed and, as a result, the cylinder jacket is widened or, depending upon the relative direction of rotation, decreased in diameter. By such a diameter adjustment, it is possible to adapt to or match the thickness of the printing material or stock. In the heretofore known construction, the cylinder jacket is disadvantageously formed of relatively thin material, such as chromium foil, for example, which is supported from below only locally and, in this respect, has a polygonal contour. Moreover, in the event of a pointwise or punctiform load, the chromium foil and the appertaining supporting sheetmetal are dented and damaged. This can occur even from one crumpled sheet, for example. In the region of the fastening location, the heretofore known embodiment has no roundness.